/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System;

namespace Lucene.Net.Analysis
{
	
    /// <summary>A TokenStream enumerates the sequence of tokens, either from
    /// fields of a document or from query text.
    /// <p>
    /// This is an abstract class.  Concrete subclasses are:
    /// <ul>
    /// <li>{@link Tokenizer}, a TokenStream
    /// whose input is a Reader; and
    /// <li>{@link TokenFilter}, a TokenStream
    /// whose input is another TokenStream.
    /// </ul>
    /// </summary>
	
    public abstract class TokenStream
    {
        /// <summary>Returns the next token in the stream, or null at EOS. </summary>
        public abstract Token Next();
		
        /// <summary>Releases resources associated with this stream. </summary>
        public virtual void  Close()
        {
        }
    }
}